Stroke-Related Changes in the Complexity of Muscle Activation during Obstacle Crossing Using Fuzzy Approximate Entropy Analysis.

Ying Chen,Huijing Hu,Rong Song,Le Li,Chenming Ma,Yinwei Zhan,Na Chen

doi:10.3389/fneur.2018.00131

Abstract

This study investigated the complexity of the electromyography (EMG) of lower limb muscles when performing obstacle crossing tasks at different heights in poststroke subjects versus healthy controls. Five poststroke subjects and eight healthy controls were recruited to perform different obstacle crossing tasks at various heights (randomly set at 10, 20, and 30% of the leg’s length). EMG signals were recorded from bilateral biceps femoris (BF), rectus femoris (RF), medial gastrocnemius, and tibialis anterior during obstacle crossing task. The fuzzy approximate entropy (fApEn) approach was used to analyze the complexity of the EMG signals. The fApEn values were significantly smaller in the RF of the trailing limb during the swing phase in poststroke subjects than healthy controls (p < 0.05), which may be an indication of smaller number and less frequent firing rates of the motor units. However, during the swing phase, there were non-significant increases in the fApEn values of BF and RF in the trailing limb of the stroke group compared with those of healthy controls, resulting in a coping strategy when facing challenging tasks. The fApEn values that increased with height were found in the BF of the leading limb during the stance phase and in the RF of the trailing limb during the swing phase (p < 0.05). The reason for this may have been a larger muscle activation associated with the increase in obstacle height. This study demonstrated a suitable and non-invasive method to evaluate muscle function after a stroke.

Highlights

Stroke, a leading cause of disability, often leads to functional limitations in the activity of daily living (ADL)
Significantly lower fuzzy approximate entropy (fApEn) values were found in the rectus femoris (RF) of poststroke subjects during the swing phase when compared with healthy controls (p < 0.05)
A significant increase was observed in the biceps femoris (BF) during the swing phase when the height of the obstacle increased from 10 to 30% of leg length (p < 0.05)

Summary

Introduction

A leading cause of disability, often leads to functional limitations in the activity of daily living (ADL). Stroke survivors have a high risk of falling during all poststroke stages [1]. Rehabilitation intervention offers beneficial effects on motor recovery after a stroke [3] and can reduce the risk of falling [4]. Stroke-Related Changes during Obstacle Crossing effective recovery strategies during rehabilitation to reduce the incidence of falling. Lu et al investigated the motor performance in high-functioning poststroke patients during obstacle crossing and found that stroke survivors appeared to adopt a specific symmetric kinematic strategy with an increased pelvic posterior tilt and swing hip abduction [8]. Said et al quantified the modifications of kinematic characteristics in stroke survivors during obstacle crossing and found that stroke survivors had reduced toe-obstacle clearance and closer horizontal distance after clearance with increased crossing time compared to healthy controls [9]

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Conclusion